1. Field of the Invention
The invention relates to a tray for ball grid array (BGA) devices, more particularly to a stackable tray for BGA devices.
2. Description of the Related Art
BGA devices are integrated circuit devices having a bottom surface formed with an array of ball contacts for mounting directly on a circuit board using conventional surface mounting techniques or indirectly with the use of a suitable integrated circuit socket on the circuit board.
Prior to mounting on a circuit board, BGA devices are generally placed in a tray. A conventional tray 1 for BGA devices 2 is shown in FIG. 1. As illustrated, the tray 1 is formed with a plurality of cavities 10 to receive the BGA devices 2 therein. Each of the cavities 10 has a bottom part formed with an opening 11 to receive the array of ball contacts 20 on the respective BGA device 2 therein. Inside the opening 11 of each cavity 10, a guard unit (not shown) is formed to prevent the fingers of an operator who is handling the tray 1 from scratching and damaging the ball contacts 20 of the BGA devices 2 inside the cavities 10 that are adjacent to a peripheral portion of the tray 1. However, the presence of the guard unit in the opening 11 of each cavity 10 arises in the following drawbacks:
Identification marks of a BGA device 2 are usually printed on a top side of the latter. BGA devices 2 of the same type are placed on the same tray 1 to facilitate use of the same. During the production of electronic equipment, trays 1 that respectively contain different BGA devices 2 may be stacked one on top of the other to facilitate transfer of the BGA devices 2 from one location to another. The guard units in the openings 11 in an upper tray 1 of the stack hinder visibility of the identification marks on the BGA devices 2 on a lower tray 1 of the stack, thereby resulting in the need to remove the upper tray 1 to identify the BGA devices 2 on the lower tray 1.